package org.framework.customutil.endecryption.rsa;

import java.io.ByteArrayOutputStream;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
 
import javax.crypto.Cipher;

import org.apache.commons.net.util.Base64;
import org.framework.customutil.endecryption.Config;

/**
 * @Title: RSAHelper.java .<br>
 * @Package org.framework.customutil.endecryption.rsa .<br>
 * @Description: RSA加密解密工具类 .<br>
 * @author 郑成功 .<br>
 * @email a876459952@qq.com .<br>
 * @date 2020-3-11 下午4:40:49.<br>
 * @version V1.0.<br>
 */
public class RSAHelper {
	
	private static final String MD5_WITH_RSA = "MD5withRSA";
	
	private static final String RSA = Config.type.RSA.toString();
	
	/**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;

    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;

    /**
     * 获取密钥对
     * @return 密钥对
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
    public static KeyPair getKeyPair() throws Exception {
        KeyPairGenerator generator = KeyPairGenerator.getInstance(RSA);
        generator.initialize(1024);
        return generator.generateKeyPair();
    }

    /**
     * 获取私钥
     * 
     * @param privateKey 私钥字符串
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
    public static PrivateKey getPrivateKey(String privateKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
        return keyFactory.generatePrivate(keySpec);
    }

    /**
     * @Description: 获取公钥 .<br>
     * @param publicKey 公钥字符串 .<br>
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
    public static PublicKey getPublicKey(String publicKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
        return keyFactory.generatePublic(keySpec);
    }
    
    /**
     * @Description: 获取公钥(Base64编码) .<br>
     * @param keyPair 密钥对.<br>
     * @return 字符串公钥.<br>   
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
  	public static String getPublicKey(KeyPair keyPair){
  		PublicKey publicKey = keyPair.getPublic();
  		byte[] bytes = publicKey.getEncoded();
  		return byte2Base64(bytes);
  	}
  	
  	/**
  	 * @Description: 获取私钥(Base64编码) .<br>
  	 * @param keyPair 密钥对.<br>
  	 * @return 字符串私钥.<br>   
  	 * @author zcg .<br>
  	 * @date 2020-3-11 下午4:43:55.<br>
  	 */
  	public static String getPrivateKey(KeyPair keyPair){
  		PrivateKey privateKey = keyPair.getPrivate();
  		byte[] bytes = privateKey.getEncoded();
  		return byte2Base64(bytes);
  	}
  	
  	/**
  	 * @Description: 字节数组转Base64编码 .<br>
  	 * @param bytes 字节数组 .<br>
  	 * @return Base64加密后的字符串.<br>   
  	 * @author zcg .<br>
  	 * @date 2020-3-11 下午4:44:56.<br>
  	 */
  	public static String byte2Base64(byte[] bytes){
  		return new String(Base64.encodeBase64(bytes));
  	}
  	
  	/**
  	 * @Description: Base64编码转字节数组 .<br>
  	 * @param base64Key base64的字符串.<br>
  	 * @author zcg .<br>
  	 * @date 2020-3-11 下午4:45:39.<br>
  	 */
  	public static byte[] base642Byte(String base64Key){
  		return Base64.encodeBase64(base64Key.getBytes());
  	}
    
    /**
     * @Description: RSA加密 .<br>
     * @param data 待加密数据
     * @param publicKey 公钥
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
    public static String encrypt(String data, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        int inputLen = data.getBytes().length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offset = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offset > 0) {
            if (inputLen - offset > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data.getBytes(), offset, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data.getBytes(), offset, inputLen - offset);
            }
            out.write(cache, 0, cache.length);
            i++;
            offset = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        // 获取加密内容使用base64进行编码,并以UTF-8为标准转化成字符串
        // 加密后的字符串
        return new String(Base64.encodeBase64String(encryptedData));
    }

    /**
     * @Description: RSA解密  .<br>
     * @param data 待解密数据  .<br>
     * @param privateKey 私钥  .<br>
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
    public static String decrypt(String data, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance(RSA);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] dataBytes = Base64.decodeBase64(data);
        int inputLen = dataBytes.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offset = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offset > 0) {
            if (inputLen - offset > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
            }
            out.write(cache, 0, cache.length);
            i++;
            offset = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        // 解密后的内容 
        return new String(decryptedData, "UTF-8");
    }

    /**
     * @Description: 签名 .<br>
     * @param data 待签名数据 .<br>
     * @param privateKey 私钥 .<br>
     * @return 签名 .<br>
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
    public static String sign(String data, PrivateKey privateKey) throws Exception {
        byte[] keyBytes = privateKey.getEncoded();
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PrivateKey key = keyFactory.generatePrivate(keySpec);
        Signature signature = Signature.getInstance(MD5_WITH_RSA);
        signature.initSign(key);
        signature.update(data.getBytes());
        return new String(Base64.encodeBase64(signature.sign()));
    }

    /**
     * @Description: 验签 .<br>
     * @param srcData 原始字符串 .<br>
     * @param publicKey 公钥 .<br>
     * @param sign 签名 .<br>
     * @return 是否验签通过 .<br>
     * @author zcg .<br>
     * @date 2020-3-11 下午4:41:13.<br>
     */
    public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {
        byte[] keyBytes = publicKey.getEncoded();
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PublicKey key = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(MD5_WITH_RSA);
        signature.initVerify(key);
        signature.update(srcData.getBytes());
        return signature.verify(Base64.decodeBase64(sign.getBytes()));
    }

    public static void main(String[] args) {
    	Map<String,Object> map = new HashMap<String, Object>();
		map.put("userId", 1);
		map.put("re", "http://www.baidu.com");
        try {
            // 生成密钥对
            KeyPair keyPair = getKeyPair();
            String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));
            String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));
            System.out.println("私钥:" + privateKey);
            System.out.println("公钥:" + publicKey);
            // RSA加密
            String data = "待加密的文字内容";
            data = map.toString();
            String encryptData = encrypt(data, getPublicKey(publicKey));
            System.out.println("加密后内容:" + encryptData);
            // RSA解密
            String decryptData = decrypt(encryptData, getPrivateKey(privateKey));
            System.out.println("解密后内容:" + decryptData);
            
            // RSA签名
            String sign = sign(data, getPrivateKey(privateKey));
            // RSA验签
            boolean result = verify(data, getPublicKey(publicKey), sign);
            System.out.print("验签结果:" + result);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.print("加解密异常");
        }
    }
	
}

